More than $100bn will be invested in aviation infrastructure in the GCC over the next few years to cope with passenger numbers that have grown annually by 10 percent, a new report has said.

Kuwait Financial Centre (Markaz) said major spending was still needed in the region as the UAE stood alone as the only Gulf state with spare capacity at its airports.

Its report said that current capacity utilisation in the GCC stood at more than 115 percent.

The study said Bahrain had the most severe case of under-capacity, moving double its capacity in 2010.

The UAE, which has seen massive airport expansions in recent years, is the only GCC country, operating below full capacity (84 percent).

Expansions at Dubai International Airport has seen capacity rise from 22 million passengers a year to 60 million with an expectation of a further increase to 90 million by 2020.

"Consequently, GCC governments have ratcheted up investment in the upgradation and expansion of airports to satisfy existing demand and achieve future strategic goals," Markaz said.

"These investments are in the neighbourhood of $104bn over the coming few years, concentrated primarily in the UAE," it added.

By 2020, the report said Emirates, Qatar, and Etihad will have the capacity to carry nearly 200 million passengers: four times their current capacity.

By 2015, the Dubai, Doha, and Abu Dhabi airports will reach an annual capacity of 190 million passengers, it added.

The report said high oil prices and sustained government support had turned airlines like Emirates, Qatar Airways and Etihad into global players.

It added that passenger traffic in the GCC had grown at an annual rate of 10 percent between 2002 and 2010 —significantly higher than global traffic growth in the same period of between 1-3 percent.

Airbus predicts that by 2028 the Middle East fleet will treble in size while Boeing forecasts that the Middle Eastern airlines will require 2,340 aircraft by 2029 at a total value of $390bn.

The International Air Transport Association (IATA) has downgraded expected profits in 2011 for Middle East airlines from $800m to $100m, mainly due to unrest in the region.

Currently, there are 37 main civil airports in the GCC region. Of these, more than 30 are in Saudi Arabia and the UAE. Saudi Arabia has four international airports and 22 domestic airports; its international airports account for 85 percent of passenger traffic.